A. Field of the Invention
This invention relates to valves for the control of the flow of fluids (liquids, gases, etc.) and more particularly to a valve having a flow blocking rotary body.
B. Description of the Related Art
Valves are mechanical devices for the control of the flow or pressure of the fluids in a pipeline or between components of a machine. They may be automatic, such as those operated by pressure against a spring behind it, or non-automatic, such as a stop-cock operated by turning a wheel.
The typical complete valve consists of an actuator and a valve body. The body is a pressure tight fitting that contains a variable orifice through which the liquid passes by, and an actuator, which provides the power to move a plug or baffle to vary the flow area of the orifice. The motion of the operator is transmitted through a stuffing box or bellows seal in the body wall to move the valve plug.
The most common types of valve designs are the butterfly valve, diaphragm valve and the sliding-stem body valve.
The butterfly valve comprises a valve body having a plug disc rotary mounted on a shaft passing diametrically trough said disc, changing from an open to a closed state by rotating said plug disc over its own axis. This type of valve has the advantage that it is economical in large sizes and can be rubber lined to provide tight shutoff; however it is not suitable for fluids at a high pressures mainly because the plug disc has a tendency to rotate when a high pressure is applied to the plug disc, causing the valve to open at an undesired rate.
The diaphragm valve comprises a main body having an orifice including an elastic diaphragm which is pushed against the orifice by an actuator in order to interrupt the flow trough the orifice. The diaphragm can be made of many elastic materials which make this type of valve suitable to be used on slurries and or corrosive chemicals but due to the properties of the elastic materials, such as plastic, this type of valve is not suitable to use at high temperatures and pressures due to the tendency of the elastic material to soften and in extreme cases to melt or tear.
The sliding-stem valve is the most commonly used valve, often used in domestic water pipes. This type of valve has many valve body configurations, each having a flow passage inside the valve body and a plug mounted on a threaded sliding stem or actuator which slide inside the valve body and push the plug to the flow passage in order to interrupt the flow trough the passage. Usually, the plug consists of a metallic disc including a rubber seal, both having a suitable configuration adaptable to the shape of the flow passage in order to provide an adequate seal between the plug and the passage walls. This type of valve has the advantage that it is economical, simple and broadly available, but has many disadvantages. One of the most remarkable disadvantages resides on the durability of its components, for example the rubber seal, after some time of use, tends to broke or wear from the edges, causing an inefficient sealing between the plug and the passage, and the threaded sliding stem tends to loose its thread, thus losing its pushing force causing a poor sealing between the seal and the flow passage. Furthermore, as the static pressure that the valve has to bear when it is closed, without leak problems, depends on the force that the operator of the valve applies to the actuator, these operation tends to destroy the rubber seal, requiring continuous replacement thereof.
Considering the above referred problems, applicant developed a valve which:
Is suitable for using with any kind of fluid at any temperature and pressure without leak problems; PA1 Do not depend on the force which the operator has to apply to the stem for fitting the rubber seal on closing the valve to provide a reliable and efficient seal when closed; PA1 Controls and maintains the desired flow of fluid in a reliable way; and PA1 Avoids that an unauthorized person could change the flow rate set for the valve.
Applicant's valve comprises: a solid two-pieces main valve body constituted by a first valve section and a second valve section, each valve section having: a central perforation having means to retain the valve sections against rotation from one another; an internal end and an external end; and one or more fluid passages surrounding the central perforation; the external end including means to be coupled to a pipeline; a rotary dosing body to be coupled between the first valve section and the second valve sections, including: a central perforation; and one or more fluid passages surrounding the central perforation to regulate or interrupt a flow of fluid in association with the fluid passages of the first valve section and second valve section; a shaft, passing through the central perforation of the first valve section, the rotary dosing body and the second valve section, having: two ends; means to firmly coupling the first valve section, the rotary dosing body and the second valve section located at each end; and means to retain the two valve sections against rotation from one another cooperating with the means of the central perforation; and locking means to set a plurality of desired positions of the rotary dosing body to regulate the flow of fluid.
Applicant's valve achieve a longer life than that the actual valves, thanks to the low friction between its components, that is, between the dosing body which is the only movable piece of the valve and the blocking body.